Temperature Sensors and Calibration • Temperature is a "derived metrology" that requires indirect measurement. • Types of thermometers include Liquid in Glass (LIG) thermometers, resistance thermometers, and voltage difference from a thermocouple. • Thermocouples are commonly used in industry due to their Seebeck effect and use of two dissimilar metals. • Resistance thermometers like the Platinum Resistance Thermometer (PRT) are widely used due to their narrower ranges and higher cost. • Sensor selection includes correct temperature range, physical construction, and sensing length. • Temperature sensors can be calibrated by comparing them to another thermometer or at fixed points. • The International Temperature Scale of 1990 (ITS-90) is used for fixed point physical properties temperature measurement.